1. Field of the Invention
This invention relates to a device for cutting and crimping connecting terminals which are to be fitted in a connector housing installed in an automobile (hereinafter referred to as "a connecting-terminal cutting and crimping device", when applicable), and more particularly to an improvement of a connecting-terminal cutting and crimping device which cuts off a plurality of connecting terminals which are provided like a chain of rings, and crimps predetermined portions of each connecting terminal over a given covered conductor to connect the former to the latter.
2. Description of the Related Art
A plurality of connecting terminals of this type are shown in FIG. 1. The connecting terminals 10 are formed by punching a flat-plate-shaped electrically conductive material. One end portion of each connecting terminal 10 is formed into a connecting portion 12, and the other end portion, namely, its base end portion, includes a pair of core squeezing protrusions 14 which are raised to confront each other, a pair of cover squeezing protrusions 15 which are also raised to confront each other, and an elongated coupling protrusion 17. The connecting terminals 10 are coupled through the coupling protrusions 17 to one edge of a carrier plate 16 in such a manner that they are arranged in parallel at equal intervals. The carrier plate 16 has a plurality of positioning and feeding holes 18 at predetermined positions corresponding to the positions of the connecting terminals 10.
Each of the connecting terminals 10 is fixedly connected to a covered conductor 21 whose cover is removed at one end to expose a core 22. For this purpose, a connecting-terminal cutting and crimping device (a so-called "anvil crimper") which performs the cutting of the coupling protrusion 17 and the crimping of the core squeezing protrusions 14 and the cover squeezing protrusions 15 at the same time, is used as disclosed, for instance by Japanese Patent Unexamined Publication No. Hei. 3-152891. That is, with the device, the coupling protrusion 17 is cut to disconnect the connecting terminal 10 from the carrier plate 16, while the pair of core squeezing protrusions 14 and the pair of cover squeezing protrusions 15 are crimped over the covered conductor 21 whose cover has been removed at one end to expose the core 22.
The conventional connecting-terminal cutting and pressing device, as shown in FIGS. 8 and 9, includes: a lower stationary die assembly including an anvil 31; and an upper movable die assembly including a position confirming punch 41, a cutting punch 51, a cover-squeezing-protrusion crimping punch 61, and a core-squeezing-protrusion crimping punch 71. The anvil 31 is made up of a cutting die 32, and a shaping die 37. The cutting die 32 has a vertical slide groove 33, and a cutting member 34 with a slit 35 which is vertically movable and provided in the groove 33. The carrier plate 16 together with a predetermined part of the coupling protrusion 17 is fixedly inserted into the slit 35. The cutting member 34 is kept urged upwardly by a compression spring 36.
As shown in FIGS. 10(a) and 10(b), the upper surface of the shaping die 37 includes a cover-squeezing-protrusion supporting surface 38 which is set back from the upper surface and extended straightly to support the cover squeezing protrusions 15 and the predetermined part of the coupling protrusion 17, and a core-squeezing-protrusion supporting surface 39 which merges through a sloped supporting surface with the cover-squeezing-protrusion supporting surface 38. The core-squeezing-protrusion supporting surface 39 is used to support the core squeezing protrusions 14.
The position confirming punch 41 has a recess 42 formed in the bottom to detect whether or not the connecting terminal 10 to be placed on the anvil 31 is positioned as required.
The cutting punch 51 has a depressing surface 52 as its bottom. The depressing surface 52 depresses the cutting member 34, so that its cutting end 35a cuts the connecting terminal 10 off the carrier plate 16. The cover-squeezing-protrusion crimping punch 61 has a crimping surface 62 which is used to crimp the cover crimping protrusions 15 over the cover 23 of the covered conductor so that the former 15 are fixedly connected to the latter 23. The core-squeezing-protrusion crimping punch 71 also has a crimping surface 72 which is used to crimp the core squeezing protrusions 14 over the core 22 exposed so that the former 14 are fixedly connected to the latter 22.
With the above-described connecting-terminal cutting and crimping device, the connecting terminal 10 is cut off the carrier plate 16 and connected to the covered conductor 21 as follows:
First, as shown in FIG. 8, the lower stationary die assembly, namely, the anvil 31 is fixedly set, and the upper movable die assembly, namely, the position confirming punch 41, the cutting punch 51, the cover-squeezing-protrusion crimping punch 61, and the core-squeezing-protrusion crimping punch 71 are set at their operation start positions, respectively. Under this condition, the connecting terminal 10 is set on the anvil 31. More specifically, the carrier plate 16 together with the predetermined part of the coupling protrusion 17 of the connecting terminal 10 is inserted into the slit 35 of the cutting member 34, and the cover squeezing protrusions 15 and the core squeezing protrusions 14 are set on the cover-squeezing-protrusion supporting surface 38 and the core-squeezing-protrusion supporting surface 39, respectively, and accordingly the connecting portion 12 of the terminal 10 is confronted with the recess 42 of the position confirming punch 41. Thus, it is determined whether or not the connecting terminal 10 is positioned correctly.
Next, as shown in FIG. 9, the upper movable die assembly is pressed against the lower stationary assembly. In this operation, it is detected with the aid of the recess 42 of the position confirming punch 41 whether or not the connecting terminal 10 is positioned correctly. The following operations are carried out at the same time or substantially at the same time: the cutting member 34 of the cutting die 32 is depressed by the cutting punch 51 through its depressing surface 52; the coupling protrusion 17 is cut with the cutting edge 35a; the cover squeezing protrusions 15 are crimped over the cover of the end portion of the covered conductor 21 by the cover-squeezing-protrusion crimping punch 61 through its crimping surface 62; and the core squeezing protrusions 14 are crimped over the exposed core 22 of the end portion of the covered conductor 21 by the core-squeezing-protrusion crimping punch 71. Thus, the connecting terminal 10 is fixedly connected to the covered conductor 21 by being crimped on the device as shown in FIG. 11.
Thereafter, the upper movable die assembly, namely, the punches 41, 51, 61 and 71 are moved upwardly to the original positions, and the carrier plate 16 held in the slit 35 of the cutting member 34 is shifted with the aid of the positioning and feeding holes 18 until the following connecting terminal comes to the working position. Under this condition, the above-described operations are automatically carried out all over again, to connect the connecting terminal to the covered conductor. And the remaining connecting terminals are also connected to the respective covered conductors in the same manner.
However, the above-described conventional connecting-terminal cutting and crimping device suffers from the following difficulties:
As shown in FIGS. 10(a) and 10(b), the cover-squeezing-protrusion supporting surface 38 of the shaping die 37, which forms a part of the upper surface of the die 37 and supports the cover squeezing protrusions 15 and the predetermined part of the coupling protrusion 17 of the connecting terminal 10, is straight in the horizontal direction. Hence, in the case where the cover squeezing protrusions 15 of the connecting terminal 10 are straight with respect to the coupling protrusion 17, burrs are liable to be formed at the cut end of the coupling protrusion 17. The burrs may damage a rubber plug or the like when the terminal is inserted into the connector housing.
In order to eliminate this difficulty, the following method is employed. That is, as shown in FIG. 8, the cover squeezing protrusions 15 are downwardly curved with respect to the cover-squeezing-protrusion supporting surface 38. That is, the cover squeezing protrusions 15 are curved to prevent the formation of burrs at the cut end of the coupling protrusion 17. However, the method gives rise to another problem. That is, in cutting off the connecting terminal, the cover squeezing protrusions 15 thus curved act to raise the coupling protrusion 17, so that the latter 17 becomes unstable in posture. Hence, when the coupling protrusion 17 is cut, its cut end portion 17a is sharpened upwardly as shown in FIG. 11 (hereinafter referred to as "a sharp end portion 17a", when applicable). When the cover squeezing protrusions 15 are crimped over the covered conductor 21, the sharp end portion 17a may bite the surface of the cover 23 of the covered conductor 21, and at worst contacts the core 22 of the covered conductor 21, thus causing troubles such as short-circuiting.